Carton packing apparatus



L-J-ILBIOWES' Y CARTON PACKING APPARATUS Oct. 7, 1952 Filed March 24, 1947 4 sn 'z-sne et 1 Oct. 7, 1952 L. H. BQWES 2,613,021

CARTON PACKING APPARATUS Oct. 7, 1952 L. H. BOWES CARTONPACKING APARATus Filed March 24. 1947 PREJSl/RE v Oct. 7, 1952 L. m-aqwlzs 2,613,021

CA'RTON napkins APrjiAiiATUs File d'llarch 24; 1947 4. sh zs-sneet 4 PRESSURE FLU D tions for which it is designed.

Patented Oct. 7, 1952 oAnToN PACKING APPARATUS Leslie H. Bowes, Wadsworth, Ohio, assignor, by mesne assignments, to Morton Salt Company,

Chicago, 1Ill.,- a corporation of Illinois Application March 24, 1947, Serial N0.'"-736,739

, 1 This inventionrelates tocarton packing apparatus, and it has special reference to apparatus for assembling appropriate, predetermined multiples of package units, such as cartons, bags and the like of salable commodities, and inserting themintoshipping containers.

v It is known that various types of apparatus for a similar purpose havebeen devised, but such types "are ordinarily of a complicated and cumberso me nature, and are expensive to;obtain,

operate and service. 3 i

Qne object of] the present invention is to provide carton packing apparatus of relatively simple construction and few moving parts, but capable of rapidly and eiiicien'tly performing the opera-- Another object is to provide for the substitution of mechanism of substantially straight-line operation, preferably in response tdfluid-actuated means, for the complicated mechanisms of packing apparatus of types now common in the art. s a further object isto provide means whereby the arrangement ofthe units to be packed, and the progress of theirpassage through the apparatus under the influence/of thearranging and feeding mechanisms thereof will serveto control the timed actuation of such mechanism.

. The invention comprises, in a broad sense,

apparatus for receiving in succession from a suitable source. such asa travelling conveyor, a plurality of package units, arranging such units in appropriate series, assembling such seriesin multiples predetermined as adequate to fill a shipping container of selected capacity, inserting them into the container, and dischargingthe filled con- .tainerffoi subsequent closing and sealing. And it willbe; understood that these operations will be performed substantially automatically in response to oontrolmeans actuatedby'the package units, theiseries thereof, andfthe multiples of 11 Claims. (01. 226-14 such series,as long 'asthe package units are received from said source, thus requiring little attention from an operator other than the supplying and positioning ofshippingcontainers to replace those .filled, all as will be explained more fully hereinafter and finally claimed.

I In the accompanying drawings illustrating the invention, in the several figures of which like parts are similarly designated,

. Fig. 1 is a top plan view of apparatus of preferred formembodying thef eatures of the invention, an enlarged semi-diagrammatic showing of ione of the. pressurelfluid control valves being asso- 'ciatedtherewith Fig. 2 is a side elevation of the apparatus shown inFig l, i Fig.3 is a perspective view of a shipping container with a multiple of seriesof package units partially inserted therein, i i

Figs. 4 to 16 illustrate,schematically, the suc cessive steps of the package unit arranging and container filling operations of the apparatus shown in Figs. 1 and 2,

Fig. 17 is a side elevation of apparatus similar to that shown in Figs. 1 and 2 but equipped with means for holding bags, rather than packing cases, as the shippingcontainers;

Fig. 18 is an enlarged fragmentary side elevation of apparatussimilar to that of Fig. 17, but

provided with an adjustable support for, certain of the bag holding means, i i

Fig. 19 is a plan view of a modified form of packing" apparatus in accordance with the invention; I a

Fig; 19a is a schematic representation of the pressure fluid actuated and control means, and the electrical switches, elementsand wiring of the modification of Fig. 19;:and

Figs. 20 and 21 are side elevations of the opposite sides of the apparatus of Fig. 19.

Although the apparatus of the inventionmay be designed to handle various sizes of package units, and series and multiples of such units, it

will be seen that in the embodiments herein illustrated the selected'inu'ltiples comprise eighteen package units arranged inrseries of three or six package units-each, the multiples being inserted into paperboard packingwcases or shipping containers, as shown in'Fig. 3.

Referring to Figs. 1 and 2,wherein the invention is embodied in apparatus of a preferred and simpleform, it will be seen that the feed platform ortop i of the packing table has aplatform extension Zohto which package units a are fed by a travelling conveyor 3. At the side of the table opposite the'p'latform extension 2 the table top lis provided with anabutment andguide wall 4, and the opposite side of the table top has asimilar, though shorter, guide. wall- 5.

- The tabletop I and walls land 5 merge-into an open throat with its bottom wall 6 in align- :ment with and (forming a continuation of the table top I, and its side walls 1 andil, and top wall 9 converging, the side walls I and E5 constituting continuations of the guide walls 4 and 5, respectively. Adjacent to the end of the table top I opposite the throat is a pusher plate I0 carried by the piston rod ll of an air cylinder 12 and recipromember 13 biased to close the said passage by spring [3a and serving alternately to permit and interrupt entry of package units from the platform extension 2 to the table top I as the gate member reciprocates. A stop l3b limits movement of the gate member l3 under the influenceof the spring I311, and the gate member ismoved against the influence of the spring b engagement therewith of the pusher plate In;

In appropriate proximity to the throat there is arranged a holder for a packing case orshipping container, this holder preferably comprising an open framework l4 having arms [5 and I5 upstanding from its outer end and from oneside, respectively, and it is pivoted to the table at H for swinging-movement froma horizontal position (full lines Figs. 1 and 2) to a vertical position (broken lines Fig. 2):, and vice versa, in response to the functioning of an air cylinder I8. When the holder is in the vertical position (Fig. 2) the filled packing case or shipping container b will fall from it onto aconveyor I9 by which it and others previously and subsequently'filled and discharged may be transported toan appropriate closing and sealing machine (not shown).

Compressed air or other appropriate pressure motive fiuid is supplied to the cylinders l2 and I8 from a line 20; and itsadmission to and exhaust from these cylinders is controlled through electrically-actuated valves 2l and 22, respectively,

in response-to operation oIfthe switches 23 and 24, and 25, the valve 2| being a four-way valve (Fig. 1') and the valve 22 beinga three-way-va-lve of substantially thetype-shown in- Fig; 17; The switches 23 and 24 are furnished with depressor strips 26' and 21; respectively, contacted and depressed and released by the fed package units in series: and multiples thereof; andtheswitch 25' is operated by a trip arm 28 reciprocating with the 'pusher plate [0.

the platform extension 2. that there is a supply of packing cases or shipping-containersb at hand adjacent to the holder-- l'4--|5-l6 and that the machine attendant has arranged one. such case or container upon the holder with its open, top

orend embracing the throat 6-.-'!. 8-9. (see particularly: Fig. 2).

With the pusher plate retracted, and; the gate member l3 held backagainst the influence of the spring l3a, asshown particularly-in, Figs. 1, 2 and 4, it-will be apparent that an aligned series of'three of the package units a will havebeen pushed upon the table top I by action of the belt conveyor 3, in line with the pusher plate and with the leading unit of the series. pressing against the depressor strip 26 of'switch 23 tending to close this switch. Now, when, the attendant closes the main switch (not. shown) in the line 29 current will flowthrough the switch 23 to the operator of valve 21 to force the piston left-hand end of cylinder l2 and admit pressure fluid fromline 2D to the right-hand end of cylinder l2- thus toproject its piston; and advances.

the pusher plate I I so that it will move the series of three units a to the position shown in Fig. 5 in which the leading unit of the series, in passing, permits release of the depressor strip 26 and opening of the switch 23, whereupon fluid will exhaust from the right-hand end of cylinder I2 and will be admitted to the left-hand end thereof s thatthepusher plate llwillbe ret a t d to its initial position, carrying with it the gate member l3. It will be noted that when the pusher plate I!) advances, the spring l3a will cause the gate member I3 to be advanced with it to arrest feed of t package unitszeonto the table to (Fig. 5), andwhen the pusher plate is retracted the gate membenwill-alsobe retracted to permit a further seriesof package, units to feed onto the table top (Fig. 6).

operation will be repeated, step-by-step, as shown in Figs. 7 to 111, until six series of packaseunitssareinplaceupcn.the. table. top. Fla. l whereu o esthe est series. of the es x s io ed forwardby. thenusher pla e] 0.. advanc ng with t the fiveseries; pr i usly f et. the. leading unite! thez-iirst fthe sixqseries will contact andon rete the depressor strip 2 to closethe switch which h ds the valve. incylin er charg ng cond ti or: cylind r 1:2). until. a lo the ix seri soipacb aseunitsh Ve. cl a ed thedep ess r. st ipi and ve... en p ec ed. as. a omplete. mult ple of units, into the packing case: on, the holder 5r -|6 (Fi 15 Just up n. c mpletion. f this o eration the.triparm. 2,8 -Wi. .rQP n-. thesw tch 5: to permit ectuationof valve 22. oexheustthe y ind r IB of: the. ho der; and drop the holder t the vertical position; (Fi .5, and, 1 6) and dise ense e-ii ed necking ca e opene d nnp the. convey r. .9.. Immediat ly thereafte the pushe late lllwill be retracted. the holder. wil ainbeeievatedfon rec ption. of. a other neck.- ing cas and t e filling o this ase. willhe per.- formed.

Ass-h wnin F slflitheapneretns may e provided with me ns tereceivea bas instead or the-pack g case. upon the.-.h.o1der, ld end, to

cylinder 36. which may. preferably, be contro led inresponse to novementof the. holder [4. irom h rizontal t v r ical posi i n. a vice. ver e by the three-way valve 2.2- which controls admission. and. exhaust. of, pressure .iiuid. for he linder [8 (Fig. 17) Thus when, the holder is. in horizontal, position. by virtue. of. pres e. fluid. ad.- m ted cylinder 18, theclampingfeet. an and 3. I. w ll b ..f. rced. to clamping. po it n. and. hold the.- bag walls fixed a ainst the. parts of. he hr at o-in ure. p acement of the bag. during inse tion ofthe multiple of. package, unit into i and. when. the. holder initiates. its movement, to vertical position the pressure fluid will be ex hausted from cylinders I8. and 36 simultaneously, and under theinfluence of the spring 3 6athe clamping feet will be, released.

Dime-.18 modification of the cl mping mea s hown. Her prov s .is made. for vertical adjiustmentof the top 9. of the throat to, accommodateit' to the increasev in height of the package units which may occur due to...atniospheric clampingfeet carried by theunember 9'. The

clamping'feet S I andtheir asosciated parts 33, 351 and 36 maybe in arrangement similar to that describedin connectiorrwith Fig. 1'7. Obviously, theicylinders 35 and 36"wi1l-be energized and t leenergized simultaneously, and iri the same manas just described in relation to the parts of j twill be notedthattheholder "l4"'of Figs. 17 and 18 is provided with a plate'onits open framework in order that there may be adequate support for-the non-rigid wall'of the bag resting'against it.

Asshown -in Figs." l'larid 18;"thalt portionof 'thetabletop inline 'withthe platform extension.

2 may; have its surfaceprovided-with, or formed of, *a plurality of rollers 40 which will facilitate feed-of the package units from'the conveyor 3 to table-top; and atthesame time tend to prevent theirpossiblemisalignment i In -Figs. 19 to 21, a modificationembodying a 'structurahandtosome extentg a functional, de-

parturefrom the preferred embodiment of Figs 1 2and' 4: to 161s shown." In this modification the table top 41 to which the package units a are fed by a conveyor is "provided with two pusher-plates 43 and 44, "respectively, projectible and retractible ih'directions'normal to each other, i

under the influence 45and'46: g i r l The pusher plate lfifl which' carries a gate member- 41similarinrfunctionto that of Figs. 1 and Z; servesto advance series of six package unitsa step-by-stepuntil three such series are in multiple arrangement in alignment with the other pusher plates44, whereupon that pusher plate 44 :15 actuated to, advance the multiple of of their respective cylinders units: into the packing case orshipping container (Fig. 20,) positioned uponthetiltable holder48 Appropriate actuated by the cylinder 48d. switches 49, 50, 5|, 52, 53 and54a and control elements for thepusher plate andholder operating, cylinders, including suitable valves 45c, 46c .and,;48b, all as; shown in Fig; 1911132118 provided wf on-wactuation in ,al manner effectively corre spondingto the similarmeans of Figs.-11 and 2. r

; -More specifically, having, reference particuriylto Figs. 19 and 19a, the, operation of this odifiedfo'rm of the-invention is as follows: As the'flpackage, units a are fed successively; by the nvey'or 42 ontothel table top 4|, they will be fessively arranged in aligned series of six units upitsoutof line withthe pathof other units fed 'toward the table tOp, l by the conveyor 421bu't acrossi the path ofreciprocation of the pusher plate 43, anawhen the leading unit of such a series is pressed by following units against the operator of the switch'49, as shown in Fig. 19, this switchwill be closed and the solenoid operator 16f the four-wayvalvefla connected therewith areas fsferies has been pushed pastif'this operator, the switch 49' will bepermitted toOpen-and the valve 45afwill be-operated to admit pressure fluid to the forward end of the cylinder 45 to retract the pusher plate"43, thepressurefluid in the rear end of'the cylinder45 meanwhile-exhausting through thevalve 4511. Thus, with the pusherplate 43 retracted, the gate member 41 will clear the path formovement of another series of six of the package units a onto the table top 4| into the pathof reciprocation of the pusher plate 43.

These operations will be repeated'until three series of package units a have been moved forward into the path of reciprocation' of the pusher plate 44 to form a predetermined multiple of the units appropriate to fill the container b,

' and asthe leading series of such multiple strikes the operating means of theswltchesill and 5| these switches will be closed to complete'energizing circuits for the relay Rand the solenoid operator of the valve 45a, respectively. The relay Rhas twosets ofnormally :open contact-s; one

set of contacts, when closed by energization of the reiayyccm i rm j a holding circuit for relay- 3 through'the normally closed switch 53. v

"fIt will be noted that as soon as the leading series of theunits 21 operates the switches 50 and 5! the solenoidoperator of the valve 46a will be actuated to cause this valve to admit pressure 'fluid to therear end of the cylinder 46 to project its piston and'lthe pusher plate 44 forward, thus permitting'theswitch 54 toclose immediately to close an alternative circuit for energizing the solenoid operator of the valve 45a, thereby'holding thepusher plate 43 in its forwardly projected position. At the same time, the forward movement of the pusher plate 44 will cause the multiplefof package units to be projected into the container 22 supported by the tiltable holder 48 the operating cylinder 43a of which is under pressure through its three-way control valve 4817' the solenoidoperator of which is energized through the normally closed switch 52.

YWhen the multiple of package units has been 5 projected into the container 1) they will have freed thebperating means for the switch 5| and this switch will open automatically, the pusher plate 1 43 being held in its forwardly projected position,

however, through the medium of the alternative circuitalready olosed by the switch 54 through the solenoid operator of its control valve 45a. At

the limit of forward movement of the-pusher plate 44, its switch operatingarm 44a engages and opens the normally closed switches llz and '53, thereby deenergizing the solenoid operator of the valve 4% and the holding circuit of relay R.

, Thefvalveflfib is thus free for operation to exhaust the cylinder 48c and permit the tiltableholder la to drop and'discharge the filled container b onto the conveyor C. Opening of the circuit through the relay R deenergizes theasolenoid operator of'the control valve lfia ofthe cylinder 46 so that i valve may operate to causethe cylinder 46 to retract the'pusherplate 44 to its starting position. Obviously, when the pusher plate 44 isre- 'tracted, the switch 54 will beopened and the pusher plate 43 Willb retracted by operation of its Valve-controlled cylinder 45. It will'be apparent that whether the invention "is embodied in the preferred form of apparatus il lustrated i'n Figs. 1, 2 and 4 to 16, or modified as temporarily arrestedJby'thegate member 47. It

willbeunderstoddthat the operator of the switch we ss rmiart t e cper' tortzfipf the switch 23 N (Fig 1) and, hencawhen the leading unit of the shown in Figs. 19 to 21, an essential feature of "operation is the samefnamely that the package "units arefed to the apparatus singly in successioni and are then; by the apparatusjarranged 1 and. these series er: i les ensiiinllv ii tableaekms .es. ...s.ement of the, nits n seri s-.tleseri multi l s ns ire-inser ng oi n. the. eses er. cont iners bein rrned n ee e. tel e nt el e tustedrhv t e un t hemse ves ur ng er trave thre sr the, pparatus- .rreus ehene s and. rrr iii ei er s. r on: Sidered itli rthe ine le .1. the in ent n -e' eu w n fele msin som slates eqe iee s. he

ristine a para s e te d plate s. gaekese. uni s ere ed, sueees h ea s. reei reeable transvers ly asfidefirr d and sur ei nt to i r e muli n e g nits; inte. e. eenteine positioned to liemi. n. nec in a ratus a e n o su ees ive fe ing k g .ua sente. nd. aeresssaid. la orm n r de mined. d re tiert. .ree ee' s P sh means t s reke u s n ielly r l e a irrecleie rrirrreddir et en o ed a d a long stroke, control means actuatedbya package unit on said plat err i when a. rede ermine of units cons itutin a serie thereo hav been delivered tosai at orm .by sei feed means and effective for; usin ho t. strok f said pusher m s nd: con r l: mean rrd nerrd rrt of eidfi t troi-mea s aetuat d. b a Pae e unit. on said; platform when a plurality of series of units a be n-mo ed. to predete mined extent-en se platform by successive. short strokes. of said ush m s an e fec i e fe e in a ns ro esa d. u he m ens-..

3. nea ton pee in a a us; a ee l for-m, means for successively feeding package units ontoand across said; platform in predetermined direction, means for supporting a container at one end; of said platform in position to receive theref rom a group of package units com prisinga plurality of series thereof, reciprocating; pusher means; having a short stroke substantially normal to said predetermined direction of feed; and a long stroke. effective for pushing a group ofpackage units from said platform into -acontaineratsaidone end thereof, control means ctuated b a a k e. n n. i P m when a predeterminednumber-of units constitut ing aseries thereof have been delivered to said platform by said feed-means and effective for causing a. short stroke of said pusher means, and controlmeansactuated by-the leading packa e unit of a seriesof unit in the movement thereof by said pusher means on said platform Rlur.-.litxiei series. ei. units eenst u in .e

ifeiieed or ai units. ermo n ereiigthereei. iae.---.b evedte pr detered ed sa d y sn t strokes or sa d. usher nd etiesiive-ier eeu insalena ire he e. i 1-: n? eart iipeekin a pa atus, a. t d. plat= ferm mean e su es ive y i nits qrrteand. eeressseid. matt r. mined dir etieapusha me s.. e r a s sten e lvnermalf es dred termine direetie i anapavi short s reke endale rgst eke. QQEH trel: m ans; aetuete by a Pac age un r an p a m. hen a n deter-niinednumbe Qf. unit .tiriae ser es. t er of. h been. de iv red o. sa e. nlatiqrrrr. rseid teed are end-Hefner tire tor eat ries. sta t.- sirek 9 pu her means, and control means actuated by the leading peera e un t f. as ries. andme nteined actuat by. the sueeeedins. uni s .Qf; that series, he

hort; strokes of sa d. push r reen n efieetire iereau in alo streke i. saidrmsherrmeans.

f- In ar o peek n a pa atu a feed; s a rm. m ans or sue ess elv feedin acka e uni s on o and a res se elrlat erm n; predeter mined i n, 1.. er; su erting: eqr r r i r: at one nd of. id. p atfo m os tion to ec ive he fr me ro p er". aekaee QBHLS'QQQP' pr plurali of series he eof; p sher-means I o posed to. i su o t n "m ansr e rq a ls s s n ia ly no l o said pr de rm ned-d n s.- tien n having a h r trek an a ens st eke c i e fer,- p h r r a ou of packa e u its from aid l f m nt a ontainer t-said one end her co trol m ans aetu ...ed. b a ckage unit on said platform when a predetermined number of units constituting a series thereof have beendelivered to said platform by said-feed means and efiective for causing-a short stroke of said pusher means, and ac a eunit controlled means. actuated bya package. unitin its movement on. said platform by said pusher means when a plurality of series of units constituting a group thereof has been moved to predetermined extent on said platform by successive short strokes of said pusher means and effective for causing a long-stroke thereof. V

6'. In cartonpacking apparatus; a feed plat form, means for successively feeding package units onto andacross said platform in predeter mined direction, pusher means at one side of said platform reciprocable substantially normal to said predetermined dire tion, a second pusher means reciprocable substantially norma l to, said fir P er m n the letter hav n r at vel Short k effective f mev neei i l i lesetles of a k ge. unit from aid. fed. means su c ss ly e e ssei platform a d i e eiid ush r means having a relatively long stroke efiective o o i g l er o s id. s us m ans e grouper package units constituting a multiple e i o un p s t o d on, d 'nletfermby su e ve st es of id fi s her. means rk troi me ns ac a d br ka unit e 'eeid platform when. a predetermined number ofunits constituting, a series thereofihave. been delivered to saidv platformby said reed mean and eflective f a s g a oke o s dfiret she means and control means actuated by apackage uniton said p t o m hen. a. ro per pack un ts a been assembled on said platform; by successive strokes of, said first pusherv means and efiecti-ve fer eeusi ieastrekeet sariseeerrsi usher flies-as 7. In carton packing apparatus, a feed platform, means for successively feeding package units onto and across said platform in predetermined direction, pusher means reciprocable over said platform transversely to said direction of feed, control means actuated by a package unit on said platform when a predetermined number of units constituting a series thereof have been delivered to said platform by said feed means and effective for causing operation of said pusher means, the latter moving the units on saidplatform a predetermined distance, pusher means reciprocable in a direction substantially normal to the direction of operation of said first'pusher means, and control means actuated by a package unit on said platform when a plurality of series of units has been moved to predetermined position on said platform by said first pusher means and effective for causing operation of said second Pusher means. I

8. In carton packing apparatus, a feed platform, means for delivering package units tosaid platform transversely thereof and determining successive series of predetermined numbers of said units and for arranging said series in predetermined multiples constituting a group and moving the resultant group of units on said plat form lengthwise thereof, said means comprising a feed conveyor for delivering successive series of units to said platform and control means actuated by the leading unit of a series delivered to said platform and pusher means reciprocable lengthwise of said platform, and control means actuated by the units of said group on said platform after their consolidation into a group effective for causing a reciprocative movement of said pusher means sufficient to insert said group of units into a container positioned to receive it.

9. In carton packaging apparatus, a feed platform, means for feeding onto said platform at one side thereof package units arranged in successive series transversely of said platform constituting a group of units with each series thereof extending lengthwise of said platform and for moving said group lengthwise of said platform, said means comprising a feed conveyor for delivering successive series of units to said platform and control means actuated by the leading unit of a series delivered to said platform and a pusher reciprocable lengthwise of said platform, and normally ineffective control means at the other side of said platform effectively actuated by the leading unit of the series of said group at said other side of said platform and maintained effective by the succeedingunits of that series in the movement of said group on said platform lengthwise thereof, said control means beingeffective when actuated by said units of said group for causing reciprocative movement of said pusher 10 sufficient to insert said group of units into a container positioned to receive it.

10. In carton packing means, a feed platform, means for feeding package units onto said platform at one sid thereof and across said platform,

a pusher reciprocable lengthwise of said platform having a short stroke and a long stroke, control means at the other side of said platform opposed to said feed means and actuated by a package unit on said platform when a predetermined number of units constituting a series thereof have been delivered to said platform by said feed means and effective for causing a short stroke of said pusher, and normally ineffective control means at one side of said platform effectively actuated by the leading unit of the series of said group at said one side and maintained effective by the succeeding units of that series in the movement of said group on the tabl lengthwise thereof, said second control means being effective when actuated by said units of said group for causing a long stroke of said pusher.

11. In carton packing apparatus, a feed platform, means for successively feeding package units onto and across said platform in predetermined direction, reciprocating pusher means having a short stroke substantially normal to said predetermined direction of feed and a long stroke, control means actuated by a package unit on said platform when a predetermined number of units constituting a series thereof have been delivered to said platform by said feed means and, effective for causing a short stroke ofsaid pusher means, and control means operable irrespective of the number of successive short strokes of said pusher means and actuated by a package unit on said platform when a plurality of series of units has been moved to predetermined. extent on said platform by successive short strokes of said pusher means and effective for causing a long stroke of said pusher means.

LESLIE H. BOWES.

REFERENCES CITED The following references are of record in the fie of this patent:

UNITED STATES PATENTS Number Name Date 1,467,019 Tzibides Sept. 4, 1923 1,515,589 Beckmann Nov. 18, 1924 1,831,130 Mudd Nov. 10, 1931 1,935,409 Mudd Nov. 14, 1933 1,953,524 Woodward Apr. 3, 1934 2,047,272 Kimball et al July 14, 1936 2,109,294 Kimball et a1 Feb. 22, 1938 2,148,820 Kimball et a1 Feb. 28, 1939 2,350,560 Kimball et al June 6, 1944 2,470,795 Socke May 24, 1949 

